1. Field
The presently disclosed subject matter relates to vehicle position lamps using a plurality of LEDs and vehicle headlights using the position lamp, and more particularly to vehicle position lamps having a high visibility and a favorable light distribution, which can be incorporated into vehicle headlights along both front corners of a vehicle, and the vehicle headlights using the position lamps having a high visual quality, which can emit harmonious light with respect to each other.
2. Description of the Related Art
Various vehicle lamps incorporating a plurality of LEDs have became popular for vehicle signal lamps such as a stop lamp, a tail lamp and the like, because LEDs are battery friendly (lower power requirements), have long life, and are generally more eco-friendly, etc. in addition to emitting light having various color tones. For example, a conventional vehicle lamp using a plurality of LEDs is disclosed in Patent Document No. 1 (Japanese Patent No. 3,181,145). FIGS. 13a and 13b are a top view and a front cross-sectional view depicting the conventional vehicle lamp disclosed in Patent Document No. 1, respectively. The conventional vehicle lamp 30 can be used as a signal lamp such as a tail lamp, a stop lamp and the like, when red LEDs are used as the LEDs.
The vehicle lamp 30 includes: a base board 35 formed in a circular cup shape in which a bottom surface is formed in a circular stepped shape; a first circuit board 31 formed in a circular shape and being located on a central portion of the bottom surface of the base board 35; a second circuit board 32 formed in a ring shape and being located adjacent the first circuit board 31 on the bottom surface of the base board 35; a third circuit board 33 formed in a ring shape and being located adjacent the second circuit board 32 on the bottom surface of the base board 35; and a fourth circuit board 34 formed in a ring shape and being located adjacent the third circuit board 33 on the bottom surface of the base board 35.
In addition, the vehicle lamp 30 includes a plurality of LEDs 37 located on the first, second, third and fourth circuit boards 31-34, and an outer lens 36 formed in a dome shape and being located on a top surface of the base board 35 so that an inner surface having a prism surface of the outer lens 36 faces the plurality of LEDs 37. In this case, the bottom surface of the base board 35 is formed in the circular stepped shape so that each of distances between the inner surface of the outer lens 36 and the plurality of LEDs 37 becomes nearly equal to each other.
Accordingly, the conventional vehicle lamp 30 can efficiently emit light having a substantially uniform brightness from the outer lens 36 using the LEDs 37, even when the outer lens 36 is formed in the dome shape. The vehicle lamp 30 can form a light-emitting surface having an exemplary shape using the above-described structure so as to match various designs of vehicles.
Another conventional vehicle lamp using a plurality of LEDs is disclosed in Patent Document No. 2 (Japanese Patent Application Laid Open No. 2000-123610). FIGS. 14a and 14b are a front view and a side cross-sectional view depicting the other conventional vehicle lamp disclosed in Patent Document No. 2, respectively. The conventional vehicle lamp 40 can also be used as a signal lamp such as a tail lamp and the like because it may include a relative large light-emitting surface.
The vehicle lamp 40 includes an outer lens 41, a plurality of light-emitting boxes 43 arranged along the outer lens 41, and a housing 42 attaching the outer lens 41 and the plurality of light-emitting boxes 43 thereto. Each of the light-emitting boxes 43 includes an LED 44 located so as to emit light toward the outer lens 41, and a Fresnel lens 45 located in front of the LED 44 as shown in FIG. 14b. 
Therefore, the other conventional vehicle lamp 40 can emit light having a uniform brightness from the outer lens 41 using a plurality of LEDs 44, even when the outer lens 41 is formed in a curve shape. The vehicle lamp 40 can also form a light-emitting surface having an exemplary shape using the above-described structure so as to match various designs of vehicles.
The above-referenced Patent Documents are listed below, and are hereby incorporated with their English abstracts in their entireties.    1. Patent Document No. 1: Japanese Patent No. 3,181,145    2. Patent Document No. 2: Japanese Patent Application Laid Open No. 2000-123610
The Patent Documents relate to the vehicle signal lamps such as a stop lamp, a tail lamp and the like, which need a relative large light-emitting surface, and the structures disclosed in the Patent Documents may be difficult to adapt a vehicle signal lamp such as a position lamp. That is because the vehicle position lamp is frequently incorporated into a lamp room that is spaced between a housing and an outer lens covering an opening of the housing, along with a high beam headlight, a low beam headlight, a turn signal lamp, etc.
In addition, in order to perform a high visibility and a high visual quality, the vehicle position lamp trends toward a lamp having a light-emitting surface that is formed in a slender curved shape such that extends along an outer lens having a curved surface of a headlight, which fits both front corners of various vehicles. Moreover, when a high intensity discharge bulb (HID bulb) and an LED light source (in which light having a blue white color tone or a white color tone may be emitted) are used as a light source for a headlight, because light emitted from vehicle position lamps using white LEDs may harmonize with the light having a substantially white color tone emitted from the headlight, the vehicle position lamps using white LEDs can result in the headlight having a high merchantability.
However, when the vehicle position lamp having the slender curved shape is designed using the structure disclosed in Patent Document No. 1, each directional quality of light emitted from the LEDs 37 degrades in a portion having a large curved surface of the outer lens and therefore, may cause a decrease of light intensity and a variation of the light intensity of the vehicle position lamp.
Moreover, when the vehicle position lamp having the slender curved shape is designed using the structure disclosed in Patent Document No. 2, each high positional accuracy between the plurality of LEDs 44 and the plurality of Fresnel lenses 45 may be required to maintain a visibility and a visual quality of the vehicle position lamp, and thus may cause a complicated work in an assembling process, an inspection process, etc.
The disclosed subject matter has been devised to consider the above and other problems, features, and characteristics. Thus, embodiments of the disclosed subject matter can include vehicle position lamps using a plurality of white LEDs which can be formed in various slender curved shapes with a simple structure such that eases a workability in manufacturing processes, and which can provide a favorable light distribution so as to be able to perform with high visibility and a high visual quality. The disclosed subject matter can also include a vehicle headlight using the position lamp, which is configured such that it is relatively easy to incorporate along with a high beam headlight, a low beam headlight and the like in a narrow space of a lamp room created between a housing and an outer lens while fitting a curved surface of the outer lens.